Mechanism for producing and applying tear strips



Nov. 21, 1967 R. w. DAVIES 3,354,019

MECHANISM FOR PRODUCING AND APPLYING TEAR STRIPS Filed Nov. 10, 1964 2 Sheets-Sheet 1 five ml} @M, M5 mgg g gg Nov. 21, 1967 w. DAVQIES 3,354,019

MECHANISM FOR PRODUCING AND APPLYING TEAR STRIPS Filed Nov. 10, 1964 2 Sheets-Sheet 2 United States Patent 3,354,019 MECHANISM FDR PRODUCING AND APPLYING TEAR STRIPS Robert William Davies, London, England, assignor to The Molins Organisation Limited, London, England, a corporation of Great Britain Filed Nov. 10, 1964, Ser. No. 410,073 Claims priority, application Great Britain, Nov. 13, 1963, 44,733/63 7 Claims. (Cl. 156519) This invention relates to mechanism for producing tearstrips and applying the tear-strips to a web of wrapping material, and is an improvement in or modification of the invention forming the subject of our copending United States application Ser. No. 276,846 filed Apr. 30, 1963, now Patent No. 3,250,659.

The invention of our said copending application is broadly defined therein as mechanism for producing tearstrips and applying the tear-strips to a web of wrapping material, in which tear-strips are severed from a web of tear-strip material by cutting the latter transversely of its length, comprising means to continuously feed the wrapper web, a movable (e.g. rotatable) knife arranged to coact with a fixed knife to periodically sever a strip of the tear-strip material from its web, and a transfer member arranged to oscillate in timed relationship with the operation of the movable knife so as to be capable of moving a strip so severed from a position adjacent to the fixed knife into contact with the wrapper web so that it can be joined thereto, and of returning to move a further severed strip from the said position into contact with the wrapper web.

Such a mechanism has various advantages, and it may be noted that the preferred form of mechanism described in said copending application is so arranged that the tearstrip material may be supplied to the mechanism in strips of width equal to the length of tear-strip desired; this is more convenient and economical than supplying the tearstrip material in strips of width equal to that of the tearstrip desired as has been a common expedient. However, in the said preferred form of mechanism the strips are laid across the width of the wrapper web, so that said web may be kept continuously in motion as the time taken for the web to travel through the distance by which succes sive strips are to be separated is available for cutting the strip and bringing it to the wrapper web.

It is not always convenient to have the tear-strips applied across the width of the wrapper web, but once the question of applying the tear-strips parallel to the length of the wrapper web is considered, it becomes apparent that there is a difficulty in doing so unless the Wrapper web is moved intermittently, or unless gaps between the adjacent ends of successive strips can be tolerated, which is not usually the case.

Briefly, this difiiculty may be explained as follows: a certain time is necessarily required for the cutting of a strip and its transfer to the wrapper web. Once laying of one strip on the web is complete there is therefore an interval before laying of another strip can commence, and thus there will be a gap on the web between successive strips unless the web remains stationary during said interval.

It is an object of the present invention to provide an improved or modified form of mechanism which is capable of laying a succession of tear-strips on a continuously moving wrapper web, parallel to the length of the latter, without undesired gaps between successive strips.

According to the present invention, there is provided a mechanism as claimed in claim 1 of United States application Ser. No. 276,846 including a second transfer member, the two transfer members being disposed at positions ice spaced along the length of the wrapper web by a distance not less than the length of one tear-strip and operable simultaneously to move two tear-strips progressively into contact with the wrapper Web to lie parallel to the length thereof, and the knives being arranged to sever two tearstrips at a time.

It should be understood that when the spacing between the positions of the transfer members is equal to the length of one tear-strip, then there will be no gaps or overlaps between adjacent tear-strips when they have been placed on the wrapper web, but that such gaps may be created if desired by making said spacing larger.

The knives may be arranged to sever the tear-strips from a single web of tear-strip material whose width equals twice the length of a single tear-strip or from two webs each equal in width to the tear-strip length. In either case it is also preferred to employ two movable knives so that the two tear-strips of each pair are severed simultaneously, one movable knife cutting from one edge to the centre of the single web while the other movable knife cuts from the centre to the other edge. When the tear-strips are cut from a single web, a slitter in the form of a rotatable circular knife may be provided to divide the web along its centre line.

In one particularly preferred embodiment of the invention, each movable knife and each transfer member is in the form of a segment (conveniently a semi-circular segment) of a disc and each movable knife is carried on a shaft parallel to, and connected by gears with, a shaft carrying the cooperating transfer member; the gearing between said shafts is such that whenever the knife rotates, the transfer member rotates at the same speed but in the opposite sense, and said gearing also meshes with a rack extending parallel to the length of the wrapper web and at right-angles to a plane containing the axes of said two shafts, the shafts being journalled in a carriage which is reciprocable parallel to the length of said wrapper web.

By moving two tear-strips and placing them 011 the wrapper web simultaneously, at spaced positions along the length of said wrapper web, it will be appreciated that there must be a time interval after each tear-strip moving operation, to allow movement of the wrapper web to carry the tear-strip delivered by the upstream transfer member past the downstream transfer member and thus avoid overlap of tear-strips. This time interval allows for the severance of further tear-strips and proper positioning of the transfer members for delivery of the next two tear-strips, without interruption of the movement of the wrapper Web.

In order that the invention may be well understood, the afore-mentioned preferred embodiment thereof will now be described in more detail, reference being made to the accompanying drawings, in which:

FIGURE 1 is an end view, partly in section, of a mechanism embodying the invention.

FIGURE 2 is a front view, also partly in section but on a smaller scale, of the mechanism of FIGURE 1; and

FIGURES 3, 4 and 5 are diagrammatic views, showing only certain of the parts visible in FIGURE 2, in positions they assume at successive stages of operation.

Referring first to FIGURES 1 and 2, the mechanism shown comprises a carriage 1 slidably carried on two parallel horizontal rods 2. A link 3 and bell-crank 4 connect the carriage 1 to a cam-follower roller 5 which rides on a cam 6, a spring 7 serving to maintain said cam-follower roller 5 in contact with the cam 6. The bell-crank 4 has a fixed point at 43. The cam 6 is so formed as to produce a reciprocatory motion of the carriage 1, to and fro along the rods 2; the exact nature of such reciprocatory motion will be seen from the description of operation of the mechanism to be given hereinafter.

The carriage 1 carries, in suitable journals, six shafts all extending horizontally; said shafts are arranged in two sets of three, viz. a left-thand set containing shafts 8, 9, and a right-hand set containing shafts 8a, 9a, 10a, and all three shafts of each set lie in a common vertical plane extending at right-angles to the axes of the rods 2. Corresponding shafts of the two sets, moreover, lie in common horizontal planes, i.e. shafts 8 and 8a are in one horizontal plane, shafts 9, 9a in a lower horizontal plane, and shafts 10, 10a in a third horizontal plane at a lower level again. The spacing between the vertical planes of the two sets of shafts is equal to the length of one tear-strip.

Shaft 8 carries a semi-circular knife 11, shaft 9 a semicircular transfer member 12, and shaft 10 a heated sealing wheel 13, all these three parts 11, 12, 13 being in vertical alignment at the forward ends of their respective shafts (FIGURE 1). At the rear ends of the said shafts are mounted three pinions, namely pinion 14 on shaft 8, pinion 15 on shaft 9, and pinion 16 on shaft 10. The pinions 14, 15, 16 are all of the same size and number of teeth and pinions 14, 16 are both in mesh with pinion 15; the shaft 9 has a rearward extension 17 carrying a further pinion 18 which is meshed with a horizontally extending rack 19, the right-hand end (as seen in FIGURE 2) of the rack 19 carrying a cam-follower roller 20 held in engagement with a rotatable cam 21 by a compression spring 22 which urges rack 19 to the right (FIGURE 2). The cams 6, 21 are arranged to be rotated at the same speed "by common driving means (not shown).

Shafts 8a-10a have similar associated parts, to which the same references are applied, with the addition of the sufiix a. It will be appreciated, however, that there is only one rack 19, engaging pinion 18a as well as pinion 18.

Wheels 13, 13a are (as mentioned above) heated wheels, i.e. each has an internal electric heating element and is fitted with slip rings to permit current supply thereto; such wheels are well known and therefore the detailed structure of these wheels is omitted from the drawings to avoid undue complexity.

Member 12 (and member 12a) is as noted a semi-circular transfer member. Said member is provided with a plurality of ports 23 (-FIGURE 1) in its periphery, each leading to a short radial passage 24 (FIGURE 2) communicating with a port 25 (FIGURE 1) in the rear face of the member 12. A boss 26 forming part of carriage 1, and serving to support one of the journals of shaft 9, extends to the rear face of member 12. The boss 26 is however of substantially smaller diameter than the member 12 and carries a block 27 of such dimensions as to cover the rear face of member 12 (when the latter is positioned as shown in FIGURE 2) sufiiciently to prevent access of atmospheric air to the ports 25 in said rear face; the block 27 is slidable on boss 26 and is held against the rear face of member 12 by springs 28, so that an arcuate groove 29 in the front face of said block is in register with the ports 25 while the member 12 is in the position shown in FIG- URE 2. Groove 29 is connected by a passage 30 and flexible pipe 31 to a suction pum-p (not shown). Thus if a tear-strip is caused to lie around the periphery of member 12, while the latter is positioned as shown in FIG- URE 2, atmospheric pressure will act on the outer surface of the tear-strip while its inner surface, i.e. the surface in contact with member 12, will be subject to subatmosperic pressure via ports 23 and therefore the tearstrip will be pressed against the member 12.

Knives 11, 11a cooperate with a fixed knife 32 (FIG- URE l) to cut two tear-strips from a pair of 'webs 33 of tear-strip material in a manner to be described. The webs 33 are fed over a horizontal plate 34 (on which knife 32 is carried) by feed rollers 35, 36- from a supply reel (not shown).

'Each of the webs 33 is of width equal to the length of the tear-strip desired and feed rollers 35, 36 are arranged to be intermittently driven in synchronism with the rota- 4 tion of cams 6, 21; each movement of the rollers 35, 36 is such that the webs 33 are advanced by the width of a tear-strip.

The mechanism further includes two feed rollers 37, 38, mounted to either side of the carriage 1, over which a wrapper web 39 is fed; rollers 37, 38 are arranged horizontally, parallel to shafts 810, and at such a height that the wrapper web travels horizontally from roller 37 to roller 38 at the level of the highest point of wheel 13 (and wheel 13a). As will be understood from FIGURE 1, the web 39 runs over wheels 13, 13:; so that said wheels traverse the centre-line of the lower surface of said web.

After passing roller 37 and before reaching wheel 13a, the web 39 passes under an applicator wheel 4-0 which applies a narrow band of adhesive centrally on the upper surface of the web.

Finally, it will be noted that in FIGURE 1 there are shown a pair of rotary knives 41, placed between feed roller 35 and feed rollers 36 for the webs 32 of tear-strip material. The provision of knives 41 enables a single web of tear-strip material, of width equal to twice the desired length of a tear-strip, to be supplied, such double-width web is fed over roller 35 and cut along its centre line by knives 4 1 to provide the desired two webs at rollers 36.

Turning now to the operation of the mechanism whose structure has been described, the rollers 37, 38 and wheel 40 rotate continuously so that the wrapper 39 advances at a constant speed, moving from right to left as seen in: FIGURE 2.

Cams 6 and 21 also rotate continuously, and cam 6, together with spring 7, follower roller 6, bell-crank 5, and link 4, causes the carriage 1 to reciprocate on bars 2. A cycle of operation may be considered as starting with the parts in the positions shown in FIGURE 2, the carriage 1 and the rack 19 each then being positioned as far to the left as it can go. First, cam 6 and spring 7 cause the carriage 1 to move to its extreme right-hand position, while cam 21 and spring 22 maintain the rack 19 stationary. Pinion 18, meshed with the rack 19, is compelled to move with the carriage 1 in which shaft 9 is journalled, hence the pinion 18, shaft 9 and member 12 are compelled to rotate; through pinions 15, 14 the shaft 8 and knife 11 are turned, also through pinion 15, 16 the shaft 10 and Wheel 13 are also turned. The relative sizes of the parts and numbers of teeth on the pinions are so selected that, with a full movement of the carriage 1 from one extreme position to the other, each of the shafts 8, 9, 10 rotates through one half revolution (i.e. and in the course of the initial left-to-right movement of the carriage now being considered, shafts 8 and 10 rotate clockwise (still referring to FIGURE 2) while shaft 9 rotates anticlockwise.

At the start of operation, moreover, it is assumed that the webs 33 are projecting past the plane of knife 11 (and knife 11a). Now as the carriage 1 makes its movement to the right, knife 11 rotates clockwise and therefore rolls across one of the webs 33; knife 11 in cooperation with fixed knife 32 cuts the Web, severing the projecting portion thereof which falls through a short distance (see FIGURE 1) until it engages the periphery of member 12, where it is held by atmospheric pressure, due to the suction applied through ports 23. At the same time the member 12 is rolling along just below the lower surface of the web and hence at the end of the left-to-right movement of the carriage 1 the projecting portion of the web 33 has been severed to form a tear-strip which is lying around the periphery of transfer member 12. The significant parts are now placed as illustrated in FIGURE 3, the tear-strip being indicated at 42.

Next, the cam 21 and spring 22 cause the rack 19 to move to the right; the distance the rack travels is sufficient to rotate the member 12, and necessarily the knife 11 and Wheel 13, through one half-revolution, the member 12 now turning clockwise while knife 11 and wheel 12 turn anti-clockwise. The parts are thus brought to the position of FIGURE 4. There need not be a stop at this position as the next stage of operation requires a further or continued movement of the rack 19 to the right, causing a further half-revolution of each of the members 11, 12 and 13. During this stage the rack 19 should move at the speed of the wrapper web 39 (although travelling in the opposite direction) as then the periphery of member 12, at its lowest point, is at any instant equal to that of the wrapper web, and there is no relative movement between the tear-strip and wrapper web in the direction of travel of the latter. As ports 25 reach their lowest positions, they cease to communicate with the arcuate groove 29, and suction is therefore removed from the inner face of the tear-strip as it comes into contact with the web 39. Said strip is therefore laid upon the web 39, upon the band of adhesive deposited by applicator wheel 40 and the strip and web are pressed firmly together in the nip of member 12 and heated wheel 13. This pressure, together with the heat applied by heated wheel 13, acts upon the adhesive to secure the tear-strip firmly to the web.

To complete the cycle of operations, the cam 21 returns rack 19 to its extreme left-hand position, and simultaneously cam 6 returns carriage 1 to the left. The rack has to travel twice as far as the carriage, having previously made two successive moves to the right, hence during return the rack moves to the left relative to the carriage. As a result, member 12 rotates anti-clockwise, knife 11 and wheel 13 clockwise, through one half-revolution in each case and the parts are thus returned to the positions of FIGURE 2.

During the last two stages of operation, i.e. while the rack 19 makes its second move to the right and while the rack 19 and carriage 1 simultaneously return to the left, the knife 11 is out of engagement with the fixed knife 32; during the former movement knife 11 is moving anti-clockwise from the position of FIGURE 4 to that of FIGURE 5, while during the return movement knife 11 is moving clockwise from the position of FIGURE 5 to that of FIG URE 2. During either of the periods occupied by these operations, therefore, the webs 33 may be advanced and the rollers 35, 36 are accordingly arranged to turn, during one or other of these periods, through a sutficient angle to feed forward a length of web equal to the desired width of tear-strip, so that this length of web projects past the fixed knife 32 in readiness for the next cycle of operations. We prefer to arrange for this movement to occur when only the rack is moving, rather than during carriage return, as during carriage movement there is always a possibility that the relative motion between the carriage and web 33 may cause some disturbance of that Web; furthermore it is convenient to drive rollers 35, 36 (through a suitably controlled clutch or the like) from the common drive means for cams 6 and 21, and said drive means will be more lightly loaded during rack movement than when the carriage 1 is being moved, thus to drive rollers 35, 36 during rack return will tend to make more constant the loading of the drive means.

While the foregoing operations are occurring obviously the members 11a, 12a and 13a will operate exactly as do members 11, 12 and 13 respectively and simultaneously therewith. Thus whenever member 12 lays a tear-strip on web 39, a second tear-strip is laid on said web by member 12a. As the vertical planes containing the two sets of shafts 8-10, 8a16a, are separated by the length of a tear-strip, it will be apparent that teh two strips are laid simu1taneously on the wrapper web in exact end-to-end abutment. When each pair of strips has been so laid, then the strip laid by member 12a must be allowed to travel with the wrapper web 39 for a distance equal to its own length before further strips are laid on the web; further or less travel will produce overlaps or gaps respectively between the trailing stn'p (laid by member 12a) of one pair and the leading strip (laid by member 12) of the next pair. Thus the leftward movement of rack 19, the rightward movement of carriage 1, and the rightward movement of rack 19, must all occur in the time taken for the wrapper web to travel the length of one tear-strip; the leftward movement of the carriage 1, during which the strip is laid on the web, then must occupy equal time. It will be apparent that these requirements govern the design of cams 6, 21 and those interconnections of the various parts of the mechanism which determine their relative speeds.

It 'will be understood that the foregoing detailed description is given by way of example only, and indeed various changes or modifications may be made in the structure of the said mechanism without departing from the scope of the invention.

I claim:

1. Mechanism for producing tear-strips and applying the tear-strips to a web of wrapping material, in which tear-strips are severed from a web of tear-strip material by cutting the latter transversely of its length, comprising means for continuously feeding the wrapper web, means for periodically advancing a web of tear-strip material, a fixed knife, a movable knife arranged to coact with said fixed knife to periodically sever two strips from the web of tear-strip material, said movable knife and said web advancing means being arranged to operate alternately, two transfer members arranged to oscillate simultaneously in timed relationship with the operation of the movable knife so as to move the strips so severed from positions adjacent the movable knife into contact with the wrapper web, so that the said strips can be joined thereto and return to move further severed strips similarly, said two transfer members being disposed at positions spaced along the length of the wrapper web by a distance not less than the length of one tear-strip.

2. Mechanism as claimed in claim 1, in which the knives are arranged to sever the tear-strips from a single web of tear-strip material whose width equals twice the length of a single tear-strip.

3. Mechanism as claimed in claim 2, including a slitter in the form of a rotatable circular knife arranged to divide the single web along its centre line.

4. Mechanism as claimed in claim 1, in which the knives are arranged to sever the tear-strips from two webs of tear-strip material each of width equal to the tear-strip length.

5. Mechanism as claimed in claim 1, including two movable knives arranged to sever each two tear-strips simultaneously.

6. Mechanism as claimed in claim 5 in which one of the two movable knives is arranged to cut from one edge to the centre of a single web of tear-strip material and the other movable knife is arranged to cut from the centre to the other edge of said single web.

7. Mechanism as claimed in claim 6, including one shaft carrying the movable knives, a further shaft parallel to said one shaft and carrying the transfer members, each movable knife and each transfer member being in the form of a segment of a disc, gearing interconnecting said shafts so that whenever the knives rotate the transfer members rotate at the same speed but in the opposite sense, a rack extending parallel to the plane of the Wrapper web and at right-angles to a plane containing the axes of the two shafts, said rack meshing with said gearing, and a carriage reciprocable parallel to the length of the wrapper web, said shafts being journalled in said carriage.

References Cited UNITED STATES PATENTS 3,146,152 8/1964 Seragnoli 156-519 DOUGLAS J. DRUMMOND, Primary Examiner. EARL M. BERGERT, Examiner. 

1. MECHANISM FOR PRODUCING TEAR-STRIPS AND APPLYING THE TEAR-STRIPS TO A WEB OF WRAPPING MATERIAL, IN WHICH TEAR-STRIPS ARE SEVERED FROM A WEB OF TEAR-STRIP MATERIAL BY CUTTING THE LATTER TRANSVERSELY OF ITS LENGTH, COMPRISING MEANS FOR CONTINUOUSLY FEEDING THE WRAPPER WEB, MEANS FOR PERIODICALLY ADVANCING A WEB OF TEAR-STRIP MATERIAL, A FIXED KNIFE, A MOVABLE KNIFE ARRANGED TO COACT WITH SAID FIXED KNIFE TO PERIODICALLY SEVER TWO STRIPS FROM THE WEB OF TEAR-STRIP MATERIAL, SAID MOVABLE KNIFE AND SAID WEB ADVANCING MEANS BEING ARRANGED TO OPERATE ALTERNATELY, TWO TRANSFER MEMBERS ARRANGED TO OSCILLATE SIMULTANEOUSLY IN TIMED RELATIONSHIP WITH THE OPERATION OF THE MOVABLE KNIFE SO AS TO MOVE THE STRIPS SO SEVERED FROM POSITIONS ADJACENT THE MOVABLE KNIFE INTO CONTACT WITH THE WRAPPER WEB, SO THAT THE SAID STRIPS CAN BE JOINED THERETO AND RETURN TO MOVE FURTHER SEVERED STRIPS SIMILARLY, SAID TWO TRANSFER MEMBERS BEING DISPOSED AT POSITIONS SPACED ALONG THE LENGTH OF THE WRAPPER WEB BY A DISTANCE NOT LESS THAN THE LENGTH OF ONE TEAR-STRIP. 